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NPS fails with "No Domain Controller Available"

Question

I just installed the NPS for the first time on our domain and authentication fails with message " There is no domain controller available for domain tp.dom" . We have two domain controllers and both are working fine. I ran nltest with various options
and all the commands are successfully completed and finds the domain controllers. Also I can login to NPS server using TP.DOM\username. I tried few different users and it's successfully. I am not sure why NPS can't locate the
domain controller.

So I tried on a different machine and getting the same error. Both run windows 2008 R2. Our DCs are 2003 R2.

Below is the message from NPS trace.

[5424] 07-08 18:54:32:124: Failed to connect to the cached DC, try DC locator ...
[5424] 07-08 18:54:32:124: Could not open an LDAP connection to domain TP.DOM.
[5424] 07-08 18:54:32:124: NTDomain::getConnection failed: The specified domain either does not exist or could not be contacted.
[5424] 07-08 18:54:32:124: Retrying LDAP search.
[5424] 07-08 18:54:32:124: Could not open an LDAP connection to domain TP.DOM.
[5424] 07-08 18:54:32:124: NTDomain::getConnection failed: The specified domain either does not exist or could not be contacted.
[5424] 07-08 18:54:32:124: No AUTHORIZATION extensions, continuing
[5424] 07-08 18:54:32:124: Added EAP Failure packet

This might be an old thread, but it comes up high in search lists. The solution mentioned in this article didn't do it for me. It turned out I had to go in to the NPS console, right click NPS Server and click Register NPS server in Active Directory.

Thanks for that. Setup a brand new 2016 RDS farm with the GW and CB on the same server but it wouldn't authenticate me on login. Found this error in the event log and it turned out to be the NPS server needing activation., (Despite my sandpit/dev environment
not needing this!?)